How do a single change in a nitrogen base alter the formation of a resulting protein?

(a) glyceraldehyde 3-phosphate dehydrogenase.

Explanation:

Glyceraldehyde 3-phosphate dehydrogenase is the enzyme which requires inorganic phosphate (Pi) essentially for it's functioning. It catalyzes the conversion of glyceraldehyde 3-phosphate into 1,3-bisphosphoglyceric acid (1,3 BPG) during glycolysis.

All other enzymes of glycolysis use ATP for phosphorylation of their substrate but this is the only enzyme which rather uses an inorganic phosphate to phosphorylate it's substrate.